Truss bridge

en.wikipedia.org/wiki/Truss_bridge

Truss bridge of the Southern Pacific Railroad in

California for a single track railway, converted to
pedestrian use and pipeline support.

Ancestor Beam bridge

Related None

Descendant Cantilever bridge, truss arch bridge, transporter bridge, lattice

bridge

Carries Pedestrians, pipelines, automobiles, trucks, light rail, heavy rail

Span range Short to medium – not very long unless it is continuous

Material Timber, iron, steel, reinforced concrete, prestressed concrete

Movable May be movable – see movable bridge

Design effort Medium

Falsework Depends upon length, materials, and degree of prefabrication

required

Truss bridge

A truss bridge is a bridge whose load-bearing superstructure is composed of a truss, a

structure of connected elements, usually forming triangular units. The connected
elements (typically straight) may be stressed from tension, compression, or sometimes
both in response to dynamic loads. The basic types of truss bridges shown in this article
have simple designs which could be easily analyzed by 19th and early 20th-century
engineers. A truss bridge is economical to construct because it uses materials efficiently.

Design
The nature of a truss allows the analysis of its structure using a few assumptions and the
application of Newton's laws of motion according to the branch of physics known as
statics. For purposes of analysis, trusses are assumed to be pin jointed where the straight
components meet, meaning that taken alone, every joint on the structure is functionally
considered to be a flexible joint as opposed to a rigid joint with the strength to maintain
its shape, and the resulting shape and strength of the structure are only maintained by the

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interlocking of the components. This
assumption means that members of the
truss (chords, verticals, and diagonals)
will act only in tension or compression. A
more complex analysis is required where
rigid joints impose significant bending
loads upon the elements, as in a
Vierendeel truss.

In the bridge illustrated in the infobox at

the top, vertical members are in tension, lower horizontal members in tension, shear, and
bending, outer diagonal and top members are in compression, while the inner diagonals
are in tension. The central vertical member stabilizes the upper compression member,
preventing it from buckling. If the top member is sufficiently stiff then this vertical
element may be eliminated. If the lower chord (a horizontal member of a truss) is
sufficiently resistant to bending and shear, the outer vertical elements may be eliminated,
but with additional strength added to other members in compensation. The ability to
distribute the forces in various ways has led to a large variety of truss bridge types. Some
types may be more advantageous when the wood is employed for compression elements
while other types may be easier to erect in particular site conditions, or when the balance
between labor, machinery, and material costs has certain favorable proportions.

The inclusion of the elements shown is largely an engineering decision based upon
economics, being a balance between the costs of raw materials, off-site fabrication,
component transportation, on-site erection, the availability of machinery, and the cost of
labor. In other cases, the appearance of the structure may take on greater importance and
so influence the design decisions beyond mere matters of economics. Modern materials
such as prestressed concrete and fabrication methods, such as automated welding, and
the changing price of steel relative to that of labor have significantly influenced the design
of modern bridges.

Model bridges

A pure truss can be represented as a pin-jointed structure, one where the only forces on
the truss members are tension or compression, not bending. This is used in the teaching
of statics, by the building of model bridges from spaghetti. Spaghetti is brittle and
although it can carry a modest tension force, it breaks easily if bent. A model spaghetti
bridge thus demonstrates the use of a truss structure to produce a usefully strong
complete structure from individually weak elements.

History in the United States

Because wood was in abundance, early truss bridges would typically use carefully fitted
timbers for members taking compression and iron rods for tension members, usually
constructed as a covered bridge to protect the structure. In 1820 a simple form of truss,

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Town's lattice truss, was patented, and had the advantage of requiring neither high labor
skills nor much metal. Few iron truss bridges were built in the United States before 1850.

Truss bridges became a common type of bridge built from the 1870s through the 1930s.
Examples of these bridges still remain across the US, but their numbers are dropping
rapidly as they are demolished and replaced with new structures. As metal slowly started
to replace timber, wrought iron bridges in the US started being built on a large scale in the
1870s. Bowstring truss bridges were a common truss design during this time, with their
arched top chords. Companies like the Massillon Bridge Company of Massillon, Ohio, and
the King Bridge Company of Cleveland, Ohio, became well-known, as they marketed their
designs to cities and townships. The bowstring truss design fell out of favor due to a lack
of durability, and gave way to the Pratt truss design, which was stronger. Again, the bridge
companies marketed their designs, with the Wrought Iron Bridge Company in the lead. As
the 1880s and 1890s progressed, steel began to replace wrought iron as the preferred
material. Other truss designs were used during this time, including the camel-back. By the
1910s, many states developed standard plan truss bridges, including steel Warren pony
truss bridges. As the 1920s and 1930s progressed, some states, such as Pennsylvania,
continued to build steel truss bridges, including massive steel through-truss bridges for
long spans. Other states, such as Michigan, used standard plan concrete girder and beam
bridges, and only a limited number of truss bridges were built.

Roadbed types
The truss may carry its roadbed on top, in the middle, or at the bottom of the truss.
Bridges with the roadbed at the top or the bottom are the most common as this allows
both the top and bottom to be stiffened, forming a box truss. When the roadbed is atop
the truss it is called a deck truss (an example of this was the I-35W Mississippi River
bridge). When the truss members are both above and below the roadbed it is called a
through truss (an example of this application is the Pulaski Skyway), and where the
sides extend above the roadbed but are not connected, a pony truss or half-through
truss.

Sometimes both the upper and lower chords support roadbeds, forming a double-decked
truss. This can be used to separate rail from road traffic or to separate the two directions
of road traffic.

Since through truss bridges have supports located over the bridge deck, they are
susceptible to being hit by overheight loads when used on highways. The I-5 Skagit River
bridge collapsed after such a strike; before the collapse, similar incidents had been
common and had necessitated frequent repairs.[2]

Gallery
Pratt through truss of the former Seaboard Air Line Railway, located near the
village of Willow, Florida; abandoned since the mid-1980s

3/23
Deck truss railroad bridge over the Erie Canal in
Lockport, New York

The four span through truss General Hertzog Bridge over

the Orange River at Aliwal North carries vehicular traffic

The through truss Skagit River bridge on Interstate 5

collapsed after an overhead support was hit by a passing
truck

Old San Jacinto River truss bridge – Humble, Texas

Pony truss bridge of reinforced concrete

Sky Gate Bridge R at Kansai International Airport, Osaka,

Japan, is the longest double-decked truss bridge in the
world. It carries three lanes of automobile traffic on top and
two of rail below over nine truss spans.

Railroad Truss bridge over Trinity River near Goodrich,

Texas

The Hart Bridge spanning the St. Johns River in

Jacksonville, Florida, is a continuous, cantilevered truss
bridge which combines a suspended road deck on the 332-
metre (1,088 ft) main span and through truss decks on the
adjacent approach spans

A railway bridge with a rail track in Leflore County,

Mississippi

Chevelon Creek Warren Pony Truss Bridge,Chevelon Creek,

Navajo County Arizona built 1913

Side view of the iron truss railway bridge over Mura River
in Mursko Središće, Croatia

Railroad Truss Drawbridge across Buffalo Bayou—Houston

4/23
Multiple spans
Truss bridges consisting of more than one span may be either a continuous truss or a
series of simple trusses. In the simple truss design, each span is supported only at the
ends and is fully independent of any adjacent spans. Each span must fully support the
weight of any vehicles traveling over it (the live load).

In contrast, a continuous truss functions as a single rigid structure over multiple supports.
This means that the live load on one span is partially supported by the other spans, and
consequently it is possible to use less material in the truss.[3]: 168  Continuous truss bridges

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were not very common before the mid-20th century because they are statically
indeterminate, which makes them difficult to design without the use of computers.

A multi-span truss bridge may also be constructed using cantilever spans, which are
supported at only one end rather than both ends like other types of trusses. Unlike a
continuous truss, a cantilever truss does not need to be connected rigidly, or indeed at all,
at the center.[3]: 169–170  Many cantilever bridges, like the Quebec Bridge shown below,
have two cantilever spans supporting a simple truss in the center. The bridge would
remain standing if the simple truss section were removed.

A multi-span simple truss bridge, Vivekananda Setu over

the Hooghly River in Kolkata, India.

A continuous truss bridge, Kingston–Rhinecliff Bridge

over the Hudson River in New York, United States.

A cantilever truss bridge, Quebec Bridge over the Saint

Lawrence River in Quebec, Canada.

Truss types used in bridges

It has been suggested that this section be split out into another article.
(Discuss) (February 2023)

Bridges are the most widely known examples of truss use. There are many types,[4] some
of them dating back hundreds of years. Below are some of the more common designs.

Allan truss

The Allan truss, designed by Percy Allan, is partly

based on the Howe truss. The first Allan truss was
completed on 13 August 1894 over Glennies Creek at
Camberwell, New South Wales and the last Allan truss
bridge was built over Mill Creek near Wisemans Ferry
Allan truss
in 1929.[5][6] Completed in March 1895, the Tharwa
Bridge located at Tharwa, Australian Capital Territory,

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was the second Allan truss bridge to be built, the oldest surviving bridge in the Australian
Capital Territory and the oldest, longest continuously used Allan truss bridge.[7][8][9]
Completed in November 1895, the Hampden Bridge in Wagga Wagga, New South Wales,
Australia, the first of the Allan truss bridges with overhead bracing, was originally
designed as a steel bridge but was constructed with timber to reduce cost.[10] In his
design, Allan used Australian ironbark for its strength.[11] A similar bridge also designed
by Percy Allen is the Victoria Bridge on Prince Street, Picton, New South Wales. Also
constructed of ironbark, the bridge is still in use today for pedestrian and light traffic.[12]

Bailey truss

Main article: Bailey bridge

The Bailey truss was designed by the British in 1940-
1941 for military uses during World War II. A short
selection of prefabricated modular components could
be easily and speedily combined on land in various
configurations to adapt to the needs at the site and
allow rapid deployment of completed trusses. In the
image, note the use of pairs of doubled trusses to adapt
to the span and load requirements. In other
applications the trusses may be stacked vertically, and
doubled as necessary.

Bailey truss over the Meurthe

River, France

Baltimore truss

The Baltimore truss is a subclass of the Pratt truss. A

Baltimore truss has additional bracing in the lower
section of the truss to prevent buckling in the
compression members and to control deflection. It is
mainly used for rail bridges, showing off a simple and
very strong design. In the Pratt truss the intersection of
the verticals and the lower horizontal tension members are used to anchor the supports
for the short-span girders under the tracks (among other things). With the Baltimore
truss, there are almost twice as many points for this to happen because the short verticals
will also be used to anchor the supports. Thus the short-span girders can be made lighter
because their span is shorter. A good example of the Baltimore truss is the Amtrak Old
Saybrook – Old Lyme Bridge in Connecticut, United States.

Bollman truss

Main article: Bollman Truss Railroad Bridge

7/23
The Bollman Truss Railroad Bridge at Savage,
Maryland, United States is the only surviving example
of a revolutionary design in the history of American
bridge engineering. The type was named for its
inventor, Wendel Bollman, a self-educated Baltimore
engineer. It was the first successful all-metal bridge
design (patented in 1852) to be adopted and
consistently used on a railroad. The design employs
wrought iron tension members and cast iron
compression members. The use of multiple
independent tension elements reduces the likelihood of
catastrophic failure. The structure was also easy to
assemble.

The Wells Creek Bollman Bridge is the only other Bollman truss in Savage, Maryland,
US. Built in 1869, moved to Savage
bridge designed by Wendel Bollman still in existence,
in 1887. It is still in use today as a
but it is a Warren truss configuration. pedestrian bridge.
39°8′5.42″N 76°49′30.33″W

Bowstring truss

The bowstring truss bridge was patented in 1841[13]

by Squire Whipple.[14] While similar in appearance to a
tied-arch bridge, a bowstring truss has diagonal load-
bearing members: these diagonals result in a structure
that more closely matches a Parker truss or Pratt truss Bowstring truss
than a true arch.

A bowstring truss bridge, in

London, Ontario, Canada

Brown truss
Main article: Brown truss
In the Brown truss all vertical elements are under
tension, with exception of the end posts. This type of
truss is particularly suited for timber structures that
use iron rods as tension members. Brown truss

Brunel truss
See Lenticular truss below.

8/23
Burr arch truss

Main article: Burr Arch Truss

This combines an arch with a truss to form a structure
both strong and rigid.

A covered bridge with a Burr arch

truss structure (Baumgardener's
Covered Bridge located in
Lancaster County, Pennsylvania)

Cantilever truss

Main article: Cantilever bridge

Most trusses have the lower chord under tension and
the upper chord under compression. In a cantilever
truss the situation is reversed, at least over a portion
of the span. The typical cantilever truss bridge is a
"balanced cantilever", which enables the construction
to proceed outward from a central vertical spar in each Forth Bridge across the Firth of
direction. Usually these are built in pairs until the Forth in the east of Scotland
outer sections may be anchored to footings. A central
gap, if present, can then be filled by lifting a conventional truss into place or by building it
in place using a "traveling support". In another method of construction, one outboard half
of each balanced truss is built upon temporary falsework. When the outboard halves are
completed and anchored the inboard halves may then be constructed and the center
section completed as described above.

Fink truss

Main article: Fink truss

The Fink truss was designed by Albert Fink of
Germany in 1854. This type of bridge was popular with
the Baltimore and Ohio Railroad. The Appomattox Fink truss (half span and cross
High Bridge on the Norfolk and Western Railway section)
included 21 Fink deck truss spans from 1869 until their
replacement in 1886.

There are also inverted Fink truss bridges such as the Moody Pedestrian Bridge in
Austin, Texas.

Howe truss

Main article: Howe truss

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The Howe truss, patented in 1840 by Massachusetts
millwright William Howe, includes vertical members
and diagonals that slope up towards the center, the Howe truss – the diagonals are
opposite of the Pratt truss.[15]
In contrast to the Pratt under compression under balanced
truss, the diagonal web members are in compression loading
and the vertical web members are in tension. Few of
these bridges remain standing. Examples include Jay Bridge in Jay, New York;
McConnell's Mill Covered Bridge in Slippery Rock Township, Lawrence County,
Pennsylvania; Sandy Creek Covered Bridge in Jefferson County, Missouri; and Westham
Island Bridge in Delta, British Columbia, Canada.

A large timber Howe truss in a commercial building.

Jay Bridge showing the truss design.

Westham Island Bridge showing its wooden truss design.

K-truss

The K-truss is named after the K formed in each panel

by the vertical member and two oblique members.
Examples are the Südbrücke rail bridge over the River
Rhine, Mainz, Germany,[16] the bridge on I-895
(Baltimore Harbor Tunnel Thruway) in Baltimore, K-truss
Maryland, the Long–Allen Bridge in Morgan City,
Louisiana (Morgan City Bridge) with three 600-foot-
long spans, and the Wax Lake Outlet bridge in
Calumet, Louisiana[17]

I-895 K-truss

10/23
Kingpost truss
Main article: King post
One of the simplest truss styles to implement, the king
post consists of two angled supports leaning into a
common vertical support.

King post truss

Lattice truss (Town's lattice truss)

Main article: Lattice truss bridge

This type of bridge uses a substantial number of
lightweight elements, easing the task of construction.
Truss elements are usually of wood, iron, or steel.
Lattice, or Warren quadrangular
truss illustrated

The lattice truss Runcorn Railway

Bridge.

Lenticular truss
A lenticular truss bridge includes a lens-shape truss,
with trusses between an upper chord (functioning as an
arch) that curves up and then down to end points, and
a lower chord (functioning as a suspension cable) that
curves down and then up to meet at the same end
points.[19] Where the arches extend above and below
the roadbed, it is called a lenticular pony truss
bridge. The Pauli truss bridge is a specific variant of
the lenticular truss, but the terms are not
interchangeable.[19]

One type of lenticular truss consists of arcuate upper

compression chords and lower eyebar chain tension
links. Brunel's Royal Albert Bridge over the River
Tamar between Devon and Cornwall uses a single The Ouellette Bridge or Aiken
tubular upper chord. As the horizontal tension and Street Bridge in Lowell,

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compression forces are balanced these horizontal Massachusetts, built in 1883 by the
forces are not transferred to the supporting pylons (as Berlin Iron Bridge Co., is the
longest lenticular truss bridge in
is the case with most arch types). This in turn enables
the United States, with five spans,
the truss to be fabricated on the ground and then to be
as well as the second-oldest
raised by jacking as supporting masonry pylons are lenticular truss bridge in
constructed. This truss has been used in the Massachusetts.[18]
construction of a stadium,[20] with the upper chords of
parallel trusses supporting a roof that may be rolled
back. The Smithfield Street Bridge in Pittsburgh,
Pennsylvania, is another example of this type.

An example of a lenticular pony truss bridge that uses

regular spans of iron is the Turn-of-River Bridge
designed and manufactured by the Berlin Iron Bridge
Co.

The Pauli truss is a variant of the lenticular truss, "with

Royal Albert Bridge under
the top chord carefully shaped so that it has a constant
construction, 1859
force along the entire length of the truss."[19] It is
named after Friedrich Augustus von Pauli, whose 1857
railway bridge (the Großhesseloher Brücke) spanned
the Isar near Munich. (See also Grosshesselohe Isartal
station.) The term Pauli truss is not interchangeable
with the term lenticular truss and, according to
Thomas Boothby, the casual use of the term has
clouded the literature.[19] The old Großhesselohe bridge
before 1905, designed by Friedrich
von Pauli

Long truss

The Long truss was designed by Stephen H. Long in

1830. The design resembles a Howe truss, but is
entirely made of wood instead of a combination of
wood and metal.[21] The longest surviving example is
the Eldean Covered Bridge north of Troy, Ohio,
spanning 224 feet (68 m).[22] One of the earliest
examples is the Old Blenheim Bridge, which with a
span of 210 feet (64 m) and a total length of 232 feet
HAER diagram of a Long truss
(71 m) long was the second-longest covered bridge in
the United States, until its destruction from flooding in
2011.

The Busching bridge, often erroneously used as an example of a Long truss, is an example
of a Howe truss, as the verticals are metal rods.[23]

12/23
Parker (camelback) truss

"Camelback bridge" redirects here. For the concrete bridge type, see concrete curved-
chord through girder bridge.
A Parker truss bridge is a Pratt truss design with a
polygonal upper chord. A "camelback" is a subset of the
Parker type, where the upper chord consists of exactly
five segments. An example of a Parker truss is the
Traffic Bridge in Saskatoon, Canada. An example of a
camelback truss is the Woolsey Bridge near Woolsey,
Arkansas.

The Woolsey Bridge is an example

of a Parker camelback truss

Partridge truss

Designed and patented in 1872 by Reuben Partridge,

after local bridge designs proved ineffective against
road traffic and heavy rains.[24] It became the standard
for covered bridges built in central Ohio in the late
1800s and early 1900s.
Partridge truss design

Pegram truss
The Pegram truss is a hybrid between the Warren
and Parker trusses where the upper chords are all of
equal length and the lower chords are longer than the
corresponding upper chord. Because of the difference
in upper and lower chord length, each panel is not Pegram truss

square. The members which would be vertical in a

Parker truss vary from near vertical in the center of the span to diagonal near each end
(like a Warren truss). George H. Pegram, while the chief engineer of Edge Moor Iron
Company in Wilmington, Delaware, patented this truss design in 1885.[25]

The Pegram truss consists of a Parker type design with the vertical posts leaning towards
the center at an angle between 60 and 75°. The variable post angle and constant chord
length allowed steel in existing bridges to be recycled into a new span using the Pegram
truss design. This design also facilitated reassembly and permitted a bridge to be adjusted

13/23
to fit different span lengths. There are twelve known remaining Pegram span bridges in
the United States with seven in Idaho, two in Kansas, and one each in California,
Washington, and Utah.

Pennsylvania (Petit) truss

The Pennsylvania (Petit) truss is a variation on the

Pratt truss.[26] The Pratt truss includes braced diagonal
members in all panels; the Pennsylvania truss adds to
this design half-length struts or ties in the top, bottom,
or both parts of the panels. It is named after the
Pennsylvania Railroad, which pioneered this design. It
was once used for hundreds of bridges in the United
States, but fell out of favor in the 1930s, and very few
bridges of this design remain.[27] Examples of this truss
type include the Lower Trenton Bridge in Trenton,
New Jersey, the Fort Wayne Street Bridge in Goshen,
Indiana, the Schell Bridge in Northfield,
Massachusetts, the Inclined Plane Bridge in
The Fair Oaks Bridge is an example
Johnstown, Pennsylvania, the Easton–Phillipsburg
of Pennsylvania Petit truss bridge.
Toll Bridge in Easton, Pennsylvania, the Connecticut
River Bridge in Brattleboro, Vermont, the Metropolis
Bridge in Metropolis, Illinois, and the Healdsburg Memorial Bridge in Healdsburg,
California.

Post truss

A Post truss is a hybrid between a Warren truss and a

double-intersection Pratt truss. Invented in 1863 by
Simeon S. Post, it is occasionally referred to as a Post
patent truss although he never received a patent for it.
[28]
The Ponakin Bridge and the Bell Ford Bridge are
two examples of this truss. A Post truss

Pratt truss

A Pratt truss includes vertical members and

diagonals that slope down towards the center, the
opposite of the Howe truss.[15] The interior diagonals A Pratt truss
are under tension under balanced loading and vertical
elements under compression. If pure tension elements are used in the diagonals (such as
eyebars) then crossing elements may be needed near the center to accept concentrated
live loads as they traverse the span. It can be subdivided, creating Y- and K-shaped
patterns. The Pratt truss was invented in 1844 by Thomas and Caleb Pratt.[29] This truss is
practical for use with spans up to 250 feet (76 m) and was a common configuration for
railroad bridges as truss bridges moved from wood to metal. They are statically

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determinate bridges, which lend themselves well to
long spans. They were common in the United States
between 1844 and the early 20th century.[29]

Examples of Pratt truss bridges are the Governor's

Bridge in Maryland;[29] the Hayden RR Bridge in
Springfield, Oregon, built in 1882; the Dearborn River
High Bridge near Augusta, Montana, built in 1897; and
the Fair Oaks Bridge in Fair Oaks, California, built
Gatton Railway Bridge showing the
1907–09.
Pratt truss design

The Scenic Bridge near Tarkio, Montana, is an example

of a Pratt deck truss bridge, where the roadway is on
top of the truss.

Southbound XPT crossing Macleay

River Railway Bridge - a Pratt truss
design - at Kempsey, NSW,
Australia

Queenpost truss

Main article: Queen post

The queenpost truss, sometimes called "queen post"
or "queenspost", is similar to a king post truss in that
the outer supports are angled towards the center of the
structure. The primary difference is the horizontal
extension at the center which relies on beam action to Queen post truss
provide mechanical stability. This truss style is only
suitable for relatively short spans.[30]

Smith truss

The Smith truss, patented by Robert W Smith on July

16, 1867,[31] has mostly diagonal criss-crossed
supports. Smith's company used many variations of
this pattern in the wooden covered bridges it built.

While most all of the bridges built in the 19th century

in the Jackson County, Ohio, area used the Smith truss
design, the Johnson Road Covered Bridge is the last
known surviving example in the state.[32]

15/23
 Smith truss

Thacher truss
The Thacher truss [33] combines some of the
characteristics of a Pratt truss with diagonals under
tension and of a Howe truss with diagonals under
compression. It is quite rare.
A Thacher truss bridge

Truss arch

Main article: Truss arch bridge

A truss arch may contain all horizontal forces within
the arch itself, or alternatively may be either a thrust
arch consisting of a truss, or of two arcuate sections
pinned at the apex. The latter form is common when
the bridge is constructed as cantilever segments from
Truss arch bridge
each side as in the Navajo Bridge.

Vierendeel truss

Main article: Vierendeel bridge

The Vierendeel truss, unlike common pin-jointed
trusses, imposes significant bending forces upon its
members—but this in turn allows the elimination of
many diagonal elements. It is a structure where the
members are not triangulated but form rectangular
openings, and is a frame with fixed joints that are
capable of transferring and resisting bending moments.
While rare as a bridge type due to higher costs
compared to a triangulated truss, it is commonly A Vierendeel bridge
employed in modern building construction as it allows
the resolution of gross shear forces against the frame
elements while retaining rectangular openings between columns. This is advantageous
both in allowing flexibility in the use of the building space and freedom in selection of the
building's outer curtain wall, which affects both interior and exterior styling aspects.

Waddell truss

Main article: John Alexander Low Waddell

Patented 1894 (U.S. Patent 529,220); its simplicity eases erection at the site. It was
intended to be used as a railroad bridge.

One example was the Waddell "A" Truss Bridge (Parkville, Missouri).

16/23
 Waddell "A" truss (1898 bridge)

Warren truss
Main article: Warren truss
The Warren truss was patented in 1848 by James
Warren and Willoughby Theobald Monzani, and
consists of longitudinal members joined only by angled A Warren truss
cross-members, forming alternately inverted
equilateral triangle-shaped spaces along its length, ensuring that no individual strut,
beam, or tie is subject to bending or torsional straining forces, but only to tension or
compression. Loads on the diagonals alternate between compression and tension
(approaching the center), with no vertical elements, while elements near the center must
support both tension and compression in response to live loads. This configuration
combines strength with economy of materials and can therefore be relatively light. The
girders being of equal length, it is ideal for use in prefabricated modular bridges. It is an
improvement over the Neville truss which uses a spacing configuration of isosceles
triangles.

Whipple truss

A Whipple truss, named after its inventor Squire

Whipple, is usually considered a subclass of the Pratt
truss because the diagonal members are designed to
work in tension. The main characteristic of a Whipple
truss is that the tension members are elongated,
usually thin, and at a shallow angle, and cross two or
more bays (rectangular sections defined by the vertical
members).

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 Bridge L-158, a double-intersection
Whipple rail truss over the
Muscoot Reservoir in Golden's
Bridge, New York

Wichert truss

The Wichert truss is a modified type of continuous

truss which is statically determinate and helps avoid
some of the other shortcomings of continuous trusses.
[34] It was patented in 1930 by Pittsburgh-based civil

engineer Edward Martin Wichert (1883–1955).[35][36]

The defining feature of this truss type is a hinged kite-
shaped section above each intermediate support.[37]
Only about ten Wichert truss bridges were ever built,
mostly in Pennsylvania and Maryland. Of these, one of Homestead Grays Bridge over the
the best known is the Homestead Grays Bridge in Monongahela River in Pittsburgh,
Pittsburgh.[38] Pennsylvania

Truss bridge video

Driving across a truss bridge: The video shows the roadway perspective of a through truss
bridge over the Willamette River in Harrisburg, Oregon, USA. The bridge features three
simply supported Parker Truss spans.

0:22

References

Footnotes
1. ^ Science and Industry Archived 2017-02-15 at the Wayback Machine, Members of
a Truss Bridge by Benj. F. La Rue, Home Study Magazine, Published by the Colliery
Engineer Company, Vol 3, No. 2, March 1898, pages 67-68.
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 4. ^ Kirsanov, M. (2019). Planar Trusses: Schemes and Formulas. GB: Cambridge
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 25. ^ US 314262, Pegram, George H., "Truss for Roofs and Bridges", published 10-24-
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External links

Bridge Basics – A Spotter's Guide to Bridge Design – from Pghbridges.com –

Illustrates many of the various types of truss arrangements used in bridges.
Historic Bridges of Michigan and Elsewhere – Many photos of truss bridges are
available on this informative and mainly truss-focused bridge website.
Historic Bridges of Iowa – An illustrated list of different architectural bridge types
found in Iowa, USA. Many of these are truss bridges.
Historic Bridges of the U.S. – An enormous database of historic bridges. Over
17,400 truss bridges are listed here.
Iron and Early Steel Bridges of Ohio A comprehensive inventory of all remaining
truss bridges in Ohio. Includes maps, photos, and invites visitor assistance in
identifying extant or demolished bridges.

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 Matsuo Bridge Company: Bridge Types – Truss
Management Plan for Historic Bridges in Virginia: The 2017 Update—Virginia
Department of Transportation's plan for managing its historic bridges, including
metal truss bridges. The update includes sections on study findings such as "General
Issues Regarding Metal and Metal Truss Bridges (Including Potential Life Span),"
"Coatings Issues for Metal Truss Bridges: Painting, Metallizing, and Galvanizing,"
and "Truss Bridge Capacity and Overloading Potential."
structurae.de The Structurae database on bridges.

Bridge-related articles

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Structural types Arch
Beam
Box girder
Bridge–tunnel
Burr Truss
Cable-stayed
Canopy
Cantilever
Cantilever spar cable-stayed
Covered
Crib
Double-beam drawbridge
Extradosed
Jet
Log
Moon
Moveable
Bascule
Drawbridge
Folding
Retractable
Rolling
Rolling bascule
Submersible
Swing
Table
Tilt
Transporter
Vertical-lift
Multi-way
Navigable aqueduct
Pile
Pontoon
Vlotbrug
Suspension
types
Timber
Through arch
Trestle
Truss
Tubular
Viaduct
Visual index to various types

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 Lists of bridges by List of bridges
type bascule bridges
cantilever bridges
medieval stone bridges in
Germany
multi-level bridges
road–rail bridges
toll bridges
vertical-lift bridges
List of bridge–tunnels
List of lists of covered bridges

Lists of bridges by By length

size Suspension bridges
Cable-stayed bridges
Cantilever bridges
Continuous truss bridges
Arch bridges
Masonry arch bridges
Highest
Tallest

Additional lists Bridge failures

Bridge to nowhere

Category

Authority control: National Japan

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